1. Field of the Invention
The present invention relates to a semiconductor circuit device, and more particularly, to a circuit device including vertical transistors connected to buried bitlines and a method of manufacturing the circuit device.
2. Description of the Related Art
As the integration density of semiconductor devices increases, the design rule must necessarily rapidly decrease to enable the integration of more devices on a substrate with a limited area, leading to a decrease in the width and length of a cell transistor of a memory device (e.g., a DRAM). The reduction of the design rule commonly results in the generation of the short channel effect phenomenon and/or degraded current driving performance of an active device such as a transistor.
Accordingly, vertical transistors have been developed for addressing the switching performance degradation associated with miniaturization of conventional planar transistors.
Also, many attempts have been made to reduce the occupation area of peripheral circuit devices for driving a DRAM cell transistor, for example, circuit devices such as sense amplifiers that include CMOS transistors forming a balanced flip-flop structure.
It would be more favorable for the reduction of the design rule if peripheral circuits were also constructed to include vertical transistors. In particular, when a cell transistor is implemented as a vertical transistor, the occupation area of the peripheral circuit device can also be greatly reduced. Therefore, in order to implement a peripheral circuit device such as the sense amplifier in a reduced substrate area, it is favorable if the peripheral circuit region is also constructed to include vertical transistors.
However, implementation of the peripheral circuit device described above not only requires the implementation of vertical transistors in the peripheral circuit region but other critical considerations include the formation of local interconnection lines for the transistors and/or the arrangement of sense amplifiers connected to bitlines.